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![Josh Poimboeuf](/assets/img/avatar_default.png)
Convert init_kernel_text() to a global function and use it in a few places instead of manually comparing _sinittext and _einittext. Note that kallsyms.h has a very similar function called is_kernel_inittext(), but its end check is inclusive. I'm not sure whether that's intentional behavior, so I didn't touch it. Suggested-by: Jason Baron <jbaron@akamai.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/4335d02be8d45ca7d265d2f174251d0b7ee6c5fd.1519051220.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
176 lines
4.8 KiB
C
176 lines
4.8 KiB
C
/* Rewritten by Rusty Russell, on the backs of many others...
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Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/ftrace.h>
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#include <linux/memory.h>
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#include <linux/extable.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/init.h>
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#include <linux/kprobes.h>
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#include <linux/filter.h>
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#include <asm/sections.h>
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#include <linux/uaccess.h>
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/*
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* mutex protecting text section modification (dynamic code patching).
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* some users need to sleep (allocating memory...) while they hold this lock.
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*
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* Note: Also protects SMP-alternatives modification on x86.
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*
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* NOT exported to modules - patching kernel text is a really delicate matter.
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*/
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DEFINE_MUTEX(text_mutex);
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extern struct exception_table_entry __start___ex_table[];
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extern struct exception_table_entry __stop___ex_table[];
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/* Cleared by build time tools if the table is already sorted. */
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u32 __initdata __visible main_extable_sort_needed = 1;
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/* Sort the kernel's built-in exception table */
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void __init sort_main_extable(void)
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{
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if (main_extable_sort_needed && __stop___ex_table > __start___ex_table) {
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pr_notice("Sorting __ex_table...\n");
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sort_extable(__start___ex_table, __stop___ex_table);
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}
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}
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/* Given an address, look for it in the exception tables. */
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const struct exception_table_entry *search_exception_tables(unsigned long addr)
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{
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const struct exception_table_entry *e;
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e = search_extable(__start___ex_table,
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__stop___ex_table - __start___ex_table, addr);
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if (!e)
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e = search_module_extables(addr);
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return e;
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}
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int init_kernel_text(unsigned long addr)
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{
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if (addr >= (unsigned long)_sinittext &&
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addr < (unsigned long)_einittext)
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return 1;
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return 0;
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}
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int notrace core_kernel_text(unsigned long addr)
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{
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if (addr >= (unsigned long)_stext &&
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addr < (unsigned long)_etext)
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return 1;
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if (system_state < SYSTEM_RUNNING &&
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init_kernel_text(addr))
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return 1;
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return 0;
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}
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/**
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* core_kernel_data - tell if addr points to kernel data
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* @addr: address to test
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*
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* Returns true if @addr passed in is from the core kernel data
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* section.
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*
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* Note: On some archs it may return true for core RODATA, and false
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* for others. But will always be true for core RW data.
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*/
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int core_kernel_data(unsigned long addr)
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{
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if (addr >= (unsigned long)_sdata &&
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addr < (unsigned long)_edata)
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return 1;
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return 0;
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}
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int __kernel_text_address(unsigned long addr)
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{
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if (kernel_text_address(addr))
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return 1;
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/*
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* There might be init symbols in saved stacktraces.
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* Give those symbols a chance to be printed in
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* backtraces (such as lockdep traces).
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*
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* Since we are after the module-symbols check, there's
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* no danger of address overlap:
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*/
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if (init_kernel_text(addr))
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return 1;
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return 0;
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}
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int kernel_text_address(unsigned long addr)
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{
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bool no_rcu;
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int ret = 1;
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if (core_kernel_text(addr))
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return 1;
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/*
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* If a stack dump happens while RCU is not watching, then
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* RCU needs to be notified that it requires to start
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* watching again. This can happen either by tracing that
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* triggers a stack trace, or a WARN() that happens during
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* coming back from idle, or cpu on or offlining.
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*
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* is_module_text_address() as well as the kprobe slots
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* and is_bpf_text_address() require RCU to be watching.
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*/
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no_rcu = !rcu_is_watching();
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/* Treat this like an NMI as it can happen anywhere */
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if (no_rcu)
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rcu_nmi_enter();
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if (is_module_text_address(addr))
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goto out;
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if (is_ftrace_trampoline(addr))
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goto out;
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if (is_kprobe_optinsn_slot(addr) || is_kprobe_insn_slot(addr))
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goto out;
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if (is_bpf_text_address(addr))
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goto out;
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ret = 0;
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out:
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if (no_rcu)
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rcu_nmi_exit();
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return ret;
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}
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/*
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* On some architectures (PPC64, IA64) function pointers
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* are actually only tokens to some data that then holds the
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* real function address. As a result, to find if a function
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* pointer is part of the kernel text, we need to do some
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* special dereferencing first.
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*/
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int func_ptr_is_kernel_text(void *ptr)
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{
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unsigned long addr;
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addr = (unsigned long) dereference_function_descriptor(ptr);
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if (core_kernel_text(addr))
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return 1;
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return is_module_text_address(addr);
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}
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